Electric valve frequency changer



Aug 3, 19 1 3. D. M AR'EHUR 2 LECTRIC FE'ZLVE FREQUENCY CHANGER Original Filed Aug. 17, 1940 Inventof: Elrnewr- D. McArthur,

His Abbot-neg Patented Aug. 3, 1943 v UNITED" PAT mff,

n EoTRIcvALvn FBEQUENCY'CHANGER- ;f Elmer n. McArthur, Schenectady, Y., assignor New York .1

' to General Electric Company, a corporationof Application April '15, 1941;. Serial N0. 388,702,

now Patent No. 2,319,072, dated May 11, 1943, w which is a. division of applicationSerialNo. 353,133, August 17, 1940,," now Patent N04,

2,288,362, dated June 30, 1,942.- Divided and this l application April 25, 1942, Serial No. 440,429

1941, Patent No, 2,319,072, dated May ll, 1943,

' which is a division of my copending patent application Serial No. 353,133, filed August 17,

1940, Patent No; 2,288,362 dated June 30,1942.

All of the above-identified applications areassigned to the assignee of the present application. It isan object of my invention to provide a new 1 and improved electric valve frequency changer circuit. x

It is another object of my; invention to provide a new and improved electric valve frequency changer circuit which is of simple construction. and arrangement for energizing a high fre quencyload circuit from an alternating current source of commercial frequency.

It is a further object of my, invention to pro vide ,a new and improved electric valve; oscillator ing current supply circuit, and inwhich thebiasing'potential impressed on the grid of the electric valve is increased inmagnitude during the negative half cycles of applied anode-cathode voltage derived from the supply circuit thereby decreasing or limiting the magnitudfliofthe grid current and effecting a substantialtincreasein the efiiciencyof the oscillator,

Briefly stated, in the illustrated gembodiment of my invention I provide a new and improvedelectric. valve frequency changer for energizing frequency. The system comprises, a pair of grids of electronic discharge devices employed in g the oscillator are selectively increased in' magnitude during the negative or'inverse half which is energized from a single phasealternat- I tem comprises a transformer 3 having a second 1 3-:Claim's. 1250-36); I a tive unidirectional biasingpotential during the negative half cycles of. appliedf anode-cathode voltage isdisclosed and broadly claimed in my copending patent application Serial No.':388,702. The modification of my invention disclosedjand claimed hereinafter relates tothe specific controlcircuit for obtaining this type of control for.

high frequency electric fvalve generators which [are-energized from single phase-alternating curf rent supply circuits;

For a better understandingcf my 1 lvm10n; "reference may lcehad to the following d-QSQliP', tion taken in connection with the accompanying drawing, and its scopewillbe' pointed out in the appended claims, The single 'figure ofthe drawing diagrammatically illustrates an embodiment of my invention as applied toan; oscil-' lator for en'ergizingla high frequencyload cir- .cuit, such. as ,a high frequency inductive furnace, from-a single phase; alternating current source of commercial frequency, and wherein the magnitude of the biasing potentials impressed on the cycles of the voltage of source frequency,

. The single figure of. the drawing illustrates diagrarnmatically anflembodiment of my, invention as applied to an electronic or electric valve frequency, changer or oscillator for energizing. ,a, high frequency load circuit vl from a' single phase alternating cu rrent supply circuit '2. The sysary winding 4 provided With anintermediate or a :high frequency load circuit from a single phase alternating current source of. commercial electronic discharge devicesof the high vacuum type, eachincludinga control member or control grid, and whichare connected-to operate in conjunction with an oscillatory circuitor a tank circuit. Corresponding -=-principal electrodes, such as the anodes or the cathodes, are connected directly to a point of reference'potentia l or to ground, and a control circuit is provided forselectively controlling the magnitude of the negative unidirectional biasing potentials impressed on the control grids to decrease or ,limitthe grid currents .during thenegativeor inverse half cycles of anode-cathode voltage derived from the single phasesupply circuit. Thefeature bfsele'ctively increasing the magnitude of the neganeutral connection 5-;connecte'd to.;g roun d'or connected to a point of reference potential. A

"pair of electronic discharge devices 6 and 'I'are arranged to operate in a push-pull relationship and each is provided with an anode 8, a cathode -9 and a control member or control grid l0. Filtering-inductances II and I2 are connected} in series relation with the associated portions of the secondary winding 4 and electronic discharge,

devices 6 and -'l to-prevent'the' transmission' of high frequency current to transformer 3. The electronic discharge devices 6' and l are ofthe L highlvacuum type and corresponding principal electrodes, such as cathodes 9, are connected'to' thel'point of reference potential or 1 to 'ground. An oscillatory circuit. l3, comprisin'g'a'capaci tances. l4 and aninductance l5,is.coupled to the anodes 8 of the electronic dischargedevices 5 and I, through capacitances l6 and I1; The load circuitj may be energized from'theginductance [5 of theaoscillatory circuit l3} I provide acontrol circuit i8 which impresses on each of the grids ID of electric'discharge devices 6 and 1 a component of voltage derived from thesupply {circuit 2 through transforming means "which may comprise :a primary windingand a secondary winding 2|, the latter of V which is provided with an intermediate or neu- 7 tral connection 22. A resistance-23 is'connected between the neutral connection and" the ground or point of referencelpotential,and co operates with the transformingmeans 19 to provide biasing potentials for the control grids it which selectively increase in magnitude during the respective low frequency" negative half cyei cles of anode-cathode voltage appliedltol'the electronic discharge devices} 6 and =1. I'nductances 24 and 25 are connectedbetweenjthe secondary winding 2| and gridsill tnpreve'nt the transmission of the high frequency impulses oi; V 2 circuit l3 tothe transformer l9 and resistance 23; -F ilterin'g 'capajcitances 26 and-"-21 are also 7 connected to" by=pass the-high frequency impulses so that jhighfrequency voltage or current variations "are "not transmitted to; transformer 'l9forjresistance-23.

It will-be notedjthat in the-embodim'ent-of-my invention illustrated;- the current transmitted 'through'resistan'ce Z3 is exclusively-controlgrid current. 'Thait'is, the anode-cathode currents of V the electronic dischargeldevices Sand-Tare not '5 transmitted through'this resistancep The embodiment of my invention illustrated the-single figure of the 'drawingoperates to limit the 'grid currents during negative half cycles: of

anode-cathode voltage, that is"during the nega tivehalf cycles of thelow frequency components of volt'age'derived'from the supply-circuit 2. Ifhe ew i e i w m nen gv l nt l eed into control circuitd-ti by means of transformer Hi together with the high frequency excitation operate to impress onthe grids l'ii oiytheelec- {trbnic h e' eviq 1 an Q ractional biasing voltages l rtne' of the grid rectification characteristics of these electronic discharge devices. The biasing potential, or; 'potentials, appear acrossj'the terminals of resistance "23 and the associated portions of the secon daryvwinding Z i ther by selectively" produ ing the ne ireufincrease in the f'grid biasingjpoten- 'tials'a't tnenmes required.

It win' be i appreciated that by indie this type of circuit-the controi'eirmt may 'b'del signed 01 tiafi iriili only iel'ativlly small values Y of current compared withthe total oiitput of the electriclvalve oscillat'orgsince the cont'rol'cir'cuit' does notltransniit :a nyportion oiithe 'anodecathode currents and'since'the control circuit is ind p d n of th e deb hbiie -lc lq 1 F thermore, the circuit is a simple arrangement for obtaining a selective increase in; the magnitude of the biasing potentials, therebyalimiting the V magnitude of;the control grid currents and effecting a substantial improvementin the efiiciency of "the system. over that afforded by the prior art arrangements; v. y ,l l. V. -While Ihave shown and described' myinvenr -tionas appliedtoa particular system offconne'cl Ations and as embodying various devicesdiagram- 'matically shown,it.will-be obvioustoithoseskilled :in the art that changes and lmodifications may be made without departing. from my invention,

an'd L -therefore, a im in the appended claims to cover all such changes end modiiications {all within thetrue spiritand s'cope of my' lnventioneag fd g miiwlnmi g'ggnn 3 am} inciuding'azplurality What I claim as new and desire to secure by Letters Patent of the United States is:

i, In combination, a single phase alternating current supply circuit, a 'high frequency alternat- 5 ing"currentloadmircuit;electric translating apy ne'cted-t'o said'windings and different correspond- *ing principal'eiectrodes being connected direct- 1y tosaid point of reference potential; a control 20 circuit connected to the grids of the electronic discharge" devices i and exclusive 0f the anodecathode circuits of said electronic di'sc'liarge devicg tor-impressing on each ofsai'd grids a biasing'potentia-l having a greater value 'i'cluring the 5 negative half cycles oi 'voltag'e of said -=supply circuit applied across the associated principal electrodesthan that applied during the po'sitive half cycles and comprising a winding energized from said supply circuit and liaving an inter O mediate connection and a resistance connected between saidintermediate connection and said p0int=of reference potential; and m anszrercoupling said control. circuit to s'aid oscillatory circuit. 4 r

eurrene supply circuit; a high-frequency alternating current load circuit, electric translating apparatus connected between said' c'ircuits and comprising an electric oscillator. including a, pair 40 I of electricallydisplaced windings having a point Jofre'ference potentialpa pair of electronic di's charge devices each connected :to a different one of said windings andleach including a plurality of prin'cipal electrodes comprising an anode, a cathode and'a control grid andzan oscillatory-cir- 'cuit energized by said windings and saidifelec- 'tronic' discharge devices," corresponding principal "electrodes of 'said discharge -devices being; con-- nected to said windings and different correspondmgprinbipal electrodes being connected directly to said-"point of Jreference'potentiaL' axcontrol circuit co eetedlte the grids of the -electronic discharge devices and ;'exclusive {of -the=': {anode- V cathode circuits oi s d electronic dischargede- 5 vic'es fo'r impressing'on said:grids biasingpotential'shaving greater negative values 'du'ring; the

,:negative half cycles of voltage ofsaid supply circuit applied v across the associated principal eledtro'des' than that applied during the "positive 7 half cycles and comprising transforming-means energize'd iirom said supply circuit and including a'windingh'aving an intermediate connection and 'a resistance connected-between aidiintermediate connection and said point' oi referen'ce' potential,

said-oscillatory circuit." f- Y 3.- In combination, afsingle phase alternating current supply c 1 uit, aghignqrrequency alterhating current load circuit, electric translating i andmeans for-couplingsaid pmtrol circuitito r10 apparatus tonne-c eed eetweeh saia 'circuits and I ctmpr isingnn electric "oscillatorvtincluding :5, pair {er electrically displaced'llwindi'ngs:liaving a point of reference poteritial, aupair 'of -:electronictdischarge' devices each-connected toaidifierentl one paratus connected between said'circuits and comof principal electrodes comprising an anode, a

cathode and a control grid and an oscillatory circuit energized by said windings and said elec-' tronic discharge devices, corresponding principal electrodes of said discharge devices being connected to said windings and difie rent corresponding principal electrodes being connected directly to said point of reference potential, 2. control circuit connected to the grids of the electronic discharge devices and exclusive of the anode-cathode circuits of said electric discharge devices for im-' pressing on said grids biasing potentials having applied across the associated principal electrodes than that applied during the positive cycles and comprising a transformer having 7 a primary winding connected to said supply circuit and 7 having a secondary winding including an intermediate connection and' aresistance connected between said intermediate connection and said point of reference potential, andmeansfor'cou- I pling said control circuit to said oscillatory circuit. y I EIMER D. 

